Performance analysis of Wilkinson power divider and Miniaturized Wilkinson Power Divider at centre Frequency 2.14 GHz

Transcription

1 Performance analysis of Wilkinson power divider and Miniaturized Wilkinson Power Divider at centre Frequency 2.14 GHz Brajlata Chauhan 1 and S.C. Gupta 2 1 Department of Electronics & Communication Engineering, Drona s Engineering College Dehradun UK, India braj.lata@rediffmail.com 2 Department of Electronics & Communication Engineering, DIT, Dehradun, UK, India sureshprem1938@gmail.com Dheeraj Aggarwal,Vishal Kumar Srivastava, Department of Electronics & Communication Engineering DBIT, Dehradun UK, India aggarwal_aggarwal12@yahoo.com ddu.vishal@gmail.com Abstract This paper reports reported performance analysis of two microstrip Wilkinson power divider and miniaturization is achieved by substituting the quarter wave transmission lines employed in conventional Wilkinson power divider with its equal circuit consisting of two open circuit stubs and an inductor and by using high dielectric substrate as alumina with dielectric 9.6, Size of miniaturized Wilkinson power divider device is 28 % smaller than the conventional Wilkinson power divider. And the second harmonic suppression is realized in miniaturization configuration at centre frequency GHz.Its frequency response is similar to low pass filters because of inductor [1] and the dividing performance the reflection coefficient and the isolation are as better as conventional Wilkinson power divider. Keywords: Power divider / combiner, Substrate, Microstrip, ADS-2009,and simulation. 1. INTRODUCTION The Wilkinson power divider splits an input signal into two equal output signals in same phase. It also work as a combiner, that is also used to combine two equal-phase signals into a single signal in the opposite direction. Power Dividers and combiners play an important role in the design of microwave circuits and their applications are various[1,2,3]. To reduce the size of passive 3 db microstrip Wilkinson power divider, capacitor version was already proposed, but we require a power divider with extreme loss in higher frequencies especially at second 3G downlink harmonics. These dividers are available (designed) in various forms with respect to amplitude and phase of the input signal such as in-phase or zero difference, 180 o out of phase (180 o hybrids), 90 o out of phase (quadrature hybrids) and other specialized configurations and the amplitude may equal or unequal for all these cases[2,3]. This paper reports performance analysis of two Wilkinson by using alumina substrate. and to miniaturized we use an inductor and two stubs instead of transmission lines, so low pass characteristics are achieved. To fully illustrate this approach, the characteristics of miniaturized Wilkinson power divider are presented and its dimensions are compared to the conventional one. The characteristics include the calculated reflection and isolation coefficients and insertion loss. Furthermore, the miniaturized Wilkinson suppresses the second harmonics of downlink frequency band in 3G systems.

2 2. CONVENTIONAL WILKINSON POWER DIVIDER DESIGN AND PERFORMANCE ANALYSIS The Wilkinson has completely matched the output ports with sufficiently high isolation between them. This device is also potentially lossless provided that no reflected power from output ports[1-6]. Figure 1: Wilkinson power divider This divider has wide applications in microwave circuits and antenna feeds, but it has a narrow bandwidth, which has the best performance at a center frequency. Figure 2: The schematic of the conventional Wilkinson power divider. Performance of conventional Wilkinson i. Isolation Factor The isolation factor of this divider is -13.3db.If we assign the input to port 1 and outputs to ports 2 and 3, then S23 and S32 is the isolation factor with the same values due to the symmetry. Figure 3: Isolation factor. ii. Coupling Factor Corresponding to the previous port assigning, coupling factors are S 21 and S 31 with the same values due to the symmetry. The coupling factor equal to 4.6 db at the center frequency of 2140MHz has been reported. but it is considerably reduced at higher frequencies. It is equal to 19.4dB at the second harmonic.

3 Figure 4: Coupling factor 3. MINIATURIZED WILKINSON POWER DIVIDER DESIGN ANALYSIS In order to reduce the size of the Wilkinson power divider, we use equivalent circuit, instead of conventional Wilkinson branches (by ABCD matrix equalizing). The circuit consists of two stubs, one inductor and the transmission lines between them.this structure must be optimized to equalize the S parameter matrices of the conventional branch. We use ADS software for optimization purposes. After optimization, get the final values for the dimensions of the corresponding parts[1]. Alumina 9.6 is used as substrate for both power divider[7].now we substitute old branches with new one and achieve the miniaturized Wilkinson power divider shown in Figure 5. Furthermore, conventional Wilkinson power divider includes one resistant placed between its output ports with resistance of 2 Z0 = 100Ω(Z0 = 50 Ω). Line calculation for miniaturized Wilkinson - Length of the micro strip quarter wave (λ / 4) transmission line at centre frequency 2.14GHZ can be calculated by following calculation. L = λ / 4 (ε r ).5 and λ= c / f 0 L = / (9.6).5 in meter, L = mm On the schematic window, we have to drew a power divider with the help of micro strip line component. Such as Msub, termination, MLIN, MLOC, MTEE, and ground connection. Figure 5: The schematic of the miniaturized Wilkinson power divider design

4 Creating Layouts of the design for the power divider, included all the necessary routes has transmission lines so the layout should be automatic on layout window of ADS Software. Figure 6: Layout generated from the schematic design of miniaturized power divider.. 4. DIMENSIONS COMPARISON Size reduction at low microwave frequencies has been the main purpose of the novel Wilkinson power divider design. The purpose has been achieved and the comparison between the miniaturized Wilkinson and the conventional one is represented in Table 1. Table 1: Dimensions comparison of Miniaturized and conventional Wilkinson power divider. 5. SIMULATION OF THE SCHEMATICS DESIGN OF WILKINSON POWER DIVIDER OR PERFORMANCE ANALYSIS Now, the passive power divider is analyzed by ADS software in order to calculate its S parameters at 2.140GHz downlink centre frequency band. They are depicted in Figure 9 in terms of isolation factor,coupling factor and reflection coefficient. i.isolation Factor If we assign the input to port 1 and outputs to ports 2 and 3, then S23 and S32 is the isolation factor with the same values due to the symmetry. The isolation factor vs frequency is depicted in Figure 7 at 3G downlink frequency band. The isolation equal to 20.2 db at the center frequency of 2.140GHz has been reported.

5 Figure 7: Isolation factor. Figure 8: Coupling factor at wide band ii. Reflection Coefficient Corresponding to the previous port assigning, the reflection coefficients are S11 (for the input), S 22 and S 33 (for the output with the same values due to symmetry). The output and the input reflection coefficients at 3G downlink frequency band are depicted in Figure 9, Reflection equal to db for the input port and db for the output port at the center frequency of 2.140GHz has been reported. iii. Coupling Factor Corresponding to the previous port assigning, coupling factors are S 21 and S 31 with the same values due to the symmetry. The coupling factor is depicted at 3G downlink frequency band and wide frequency band in Figure 8. The coupling factor equal to db at the center frequency of 2140MHz has been reported. This value is approximately constant at the desired band, but it is considerably reduced at higher frequencies. It is equal to 17.5dB at the second harmonic frequency of 4280MHz which means that the novel Wilkinson power divider suppresses any signal at all frequencies equal and higher than this. But the coupling factor is approximately constant at lower frequency. Therefore, the frequency response of novel Wilkinson is similar to the low pass filters. Figure 9: Isolation, Reflection and Coupling factor at desired center frequency 2.14GHZ The RF input signal must be divided between in-phase and quadrature mixers in receivers based on the direct conversion configuration. These mixers are positioned at up and down places, therefore, length reduction of the divider is more important than width reduction due to the available space between the two mixers. Small width dividers are not suitable, while small length dividers are the most effective in circuit size reduction.

6 6. APPLICATION OF THIS WILKINSON IN UMTS MOBILE RECEIVERS The 3G-UMTS downlink frequency band is expanded from 2.110GHz to 2.170GHz with a center frequency of GHz, so the novel miniaturized Wilkinson power divider has been designed for this frequency band [9-10]. The RF input signal in 3G receivers must be divided between in-phase and quadrature mixers. This procedure requires a miniaturized power divider at the above mentioned frequency band. The novel Wilkinson complies with the 3G requirements and suppresses second harmonics of the 3G downlink frequency around 4.280GHz. The novel Wilkinson is suitable and applicable in the receivers integrating GSM and 3G technology due to perfect performance at 900 MHz. 7. CONCLUSION This paper reported performance analysis of two Wilkinson by using alumina substrate shows in above figure and miniaturized Wilkinson power divider at 2.140GHz has been developed. Reduction of the device size is 28 % then the conventional power divider has been achieved. REFERENCES 1.S. Shamsinejad, M. Soleimani, and N. Komjani Novel Miniaturized Wilkinson Power Divider For 3G Mobile Receivers,,Electrical Engineering Department,Iran University of Science and Technology (IUST) Tehran, Iran ( 2008). 2.Pak-Wing LI, and Kwok-Keung M. CHENG, Novel Microwave Power Divider Circuits with Unequal Dividing Ratio and Simple Layout The Chinese Univ. of Hong Kong. 3. Pozar, D. M., Microwave Engineering, Addison-Wesley Publishing Company Inc.1990, 4. Maximilian C. Scardelletti, George E. Ponchak, and Thomas M. Weller, Miniaturized Wilkinson Power Dividers Utilizing Capacitive Loading IEEE Microwave and Wireless Component Letters, VOL. 12, NO. 1, JANUARY E.J. Wilkinson, An N-Way Hvbrid Power Divider, IRE Trans. on Microwave Theory and Techniques, VO1. MTT-8, pp (January 1960).Progress In Electromagnetics Research Letters, Vol. 4, , Nishikawa, K., T. Tokumitsu, and I. Toyoda, Miniaturized Wilkinson power divider using three-dimensional MMIC technology, IEEE Microwave and Guided Wave Lett., Vol. 6, No. 10, , Oct Rozor Corporation,Rt duorite and PTFE Materials notes, Advanced Circuit Materials Division 100 S. Roosevelt Avenue, Chandler, AZ Lee, D. H., Y. B. Park, and Y. Yun, Highly miniaturized Wilkinson power divider employing pπ-type multiple coupled microstrip line structure, Electronics Letters, Vol. 42, No. 13, June 22, GPP TS V5.2.0 ( ) Technical Specification Group Radio Access Networks; UE Radio Transmission and Reception (FDD) 2002, 3GPP Organizational Partners (ARIB, CWTS, ETSI, T1, TTA,TTC). 10.Third Generation Partnership Project (3GPP), UE radio transmission and reception (FDD), Technical Specification , Vol , October 1999.

7 Authors Profile: Mrs Brajlata Chauhan received her Master degree in Digital communication from Uttrakhand technical University Dehradun Uttrakhand, India. She is working in Drona s College of Management and Technical Education Dehradun as Associate Prof. A life member of Institute of Electronics and Telecommunication Engineers India. She is having teaching experience of 07 years in Engineering Institutions.and she did this research work in Defence Electronics and Application Laboratory Dehradun (UK). Prof. (Dr.) S.C. Gupta, Professor Emeritus, IIT Roorkee, is having total experience of about 35 years as Prof. & Head Deptt of Electronics & Communication IIT Roorkee, Now he is working in DIT Dehradun as Dean (PG Course) of Electronics and communication department.